Device for detecting defective nuclear reactor fuel rods

Abstract

A moisture sensor is provided for a nuclear fuel rod for water-cooled nuclear reactors wherein moisture can be present. The fuel rod has an end cap and a charge of nuclear fuel. The moisture sensor is disposed between the end cap and the charge and serves to detect a leak in the fuel rod. The moisture sensor includes a capsule-like housing having an inner space and having openings through which moisture can pass into the inner space in the event of a leak in the fuel rod. Ferromagnetic material is disposed in the inner space of the housing together with a moisture detector responsive to moisture for altering the disposition of the ferromagnetic material in the inner space.

What is claimed is: 
     
       1. A nuclear reactor fuel rod comprising a nonmagnetic tubular jacket having an end portion, an end cap closing said end portion, nuclear fuel in said jacket, said fuel and end cap defining therebetween a space inside of said jacket, a capsule-like housing positioned in said space, said housing being made of non-magnetic material and having at least one hole formed therethrough, a mixture of aluminum powder and a water-soluble mercury compound inside of said capsule-like housing, and ferromagnetic material inside of said capsule-like housing, said housing internally forming a space into which said mixture and said material can move. 
     
     
       2. The fuel rod of claim 1 in which said mixture is in the form of a compact body. 
     
     
       3. The fuel rod of claim 2 in which said ferromagnetic material is in the form of a powdered component of said body. 
     
     
       4. The fuel rod of claim 2 in which said ferromagnetic material is in the form of a pellet abutting said body. 
     
     
       5. The fuel rod of claim 2 in which said capsulelike housing contains a cup-like container, said body forms a covering lid for said container and said ferro-magnetic material is contained in said container.